Causes of shaft current generated by Big Power Dc Motor
The current in the shaft, housing, and base circuit of the DC brushless motor controller is called the shaft current. The shaft current causes the bearing surface of the DC brushless motor controller or the ball to be eroded, forming point-like micro-holes, which deteriorates the running performance of the bearing, increases the friction loss and heat, and eventually causes the bearing to burn. The analysis found that this phenomenon originated from the following five reasons:
(1) Asymmetry of the magnetic field;
(2) There are harmonics in the supply current;
(3) The manufacturing and installation are not good, and the air gap is not uniform due to the eccentricity of the rotor;
(4) There is a gap between the two semicircles of the detachable stator core;
(5) The number of tiles having the stator cores stacked in a fan shape is not properly selected.
The DC brushless motor controller can avoid the generation of the shaft current by eliminating the pulsating flux and the power harmonic motor design, insulating the bearing housing and the base of the sliding bearing, and insulating the outer ring and the end cover of the rolling bearing.